Electromigration is a significant reliability issue in integrated circuit interconnects. Diffusion of metal atoms within a circuit trace that is conducting current may cause the line to narrow near a grain boundary in the metal. The diffusion kinetics are typically heat-dependent, with an increase of temperature leading to a greater rate of diffusion. Thus, a metal line operating at a higher temperature may experience a reduced lifetime relative to the line operating at a lower temperature.
Some integrated circuits, CPUs e.g., are commonly attached to a heat sink to reduce the operating temperature thereof. While this approach may reduce the mean operating temperature of a device, a localized source of power dissipation on the device die may lead to locally greater temperature than average. This greater temperature places interconnects near the source at risk of early failure from electromigration.